Electronic accounting machine



April 1, 1952 c. F. RENCH 2,591,007

I ELECTRONIC ACCOUNTING MACHINE Filed Dec'. 17, 1949 v4 sheets-sheet 1HIS ATTORNEYS Filed Dec. 1'7, 1949 c. F. RENCH 2,591,007

ELECTRONIC ACCOUNTING MACHINE 4 Sheets-Sheet 2 INVENTOR CARL F. RENCH BYawe/'M Mw] 7%@ HIS ATTORNEYS April 1, 1952 c. F. RENCH 2,591,007

ELECTRONIC ACCOUNTING MACHINE Filed Dec. 17, 1949 4 Sheets-Sheet 3 BYa/v@ HIS ATTORNEYS April 1, 1952 c. F. RENcl-l ELECTRONIC ACCOUNTINGMACHINE 4 Sheets-Sheet 4 Filed Deo. v17, 1949 ID p..

' CARL F. RENGH BYMZ/ M /w ZM@ HIS ATTORNEYS Patented pr. 1, 11952ELECTRONIC ACCOUNTING BIAGI-HNE Carl F. Bench, Troy, Ohio,l assigner toThe National Cash Register Company, Dayton, Ohio, a corporation ofMaryland Aapplication December 17, 1949, Serial No. 133,540 5 claims.(Cl. 2504-27) This invention r tes to electronic accounting machines andin particular to an improved controlled digital electronic impulsegenerator and ccumulator with readout and digit-manifesting meanstherefor.

The novel impulse generator is of a type which is capable of effectingentries simultaneously in a plurality of denominational orders oi anaccumulator. The impulse generator utilizes a plurality of tubes, Whichare common to a plurality of denominational orders, for producingimpulse trains corresponding to the digits 1" to 9 and containingcorresponding numbers of impulses. These impulse trains, which areavailable to the pluralit7 of denominational orders, may be selectivelyswitched to any one r more denominational output conductors of theimpulse generator by corresponding denominational digitselecting means.

The plurality of tubes of the impulse generator includes anoscillator-controlled means for producing driving impulses, a chain oftubes containing a start tube and a priming tube for each of the digitsl to 9, and an impulsetrain-producing tube for each of the primingtubes. The priming tubes are driven by the driving impulses, once thestart tube has been rendered conducting, and will become conducting oneafter another in sequence, beginning with the 9 tube and ending with thel tube. As each priming tube becomes conducting, it conditions a relatedimpulse-train-producing tube also to respond to the driving impulses andproduce an impulse train containing the number of impulses correspondingto the value of the priming tube. As soon as the impulse trains havebeen produced, the start tube and the priming tubes are returned totheir non-conducting status and made ready for another amount-enteringoperation.

The impulse-train-tube circuit provides a low impedance source for theimpulses which is capable of producing extremely strong impulses, sothat their quality will not be impaired and they will be able to producesatisfactory operation of the accumulator even though the impulses areswitched simultaneously to a plurality of denominational outputconductors to cause entries to be made in corresponding orders of theaccumulator. This circuit also minimizes cross-- talk or interferenceeffects between conductors forming the output circuits. l

The oscillator of the impulse generator is also used to control afurther impulse-generating means to provide tens-transfer-effectingimpulses for causing tens transfer entries to be made in theaccumulator, when required, and in such a manner as not to interfereWith the normal digital entries in the accumulator.

1 The novel accumulator is made up of a plurality of denominationalorders, each order of which contains an electronic coupling devicethrough which digit entries and tens transfers are made, a pair of tubesconnected as a trigger pair and operable to effect tens transfers, andfour pairs of tubes connected to operate as trigger pairs, each triggerpair being operable to an on condition and an oil condition, and furtherconnected for accumulating digit values in the decimal notation andrepresenting the units digit or the accumulated sum in that order, bypredetermined combinations of on and off conditions of the trigger pair.between the four trigger pairs, by which they are enabled to count inthe decimal notation, connect the trigger pairs in cascade and alsoprovide certain feed-back circuits, whereby the last trigger pair of thecascade, upon its being turned on can cause an automatic operation ofone of the previous trigger pairs in the cascade, and, upon its beingturned orig can cause an automatic operation of another of the previoustrigger pairs in the cascade. By separating the feed-back circuits andutilizing the on and off condition of the last trigger pair of thecascade and by providing suitable isolation resistors in conjunctionwith the feed-back circuits, the operating characteristics of theaccumulator are improved, and rectiiiers or decoupling units of thesemi-conductor or barrier layer type have lower back impedane-e, such asgermanium crystals, can be used, thereby eliminating the need for usingdiodes as rectiers or decoupling units. The trigger pairs of the cascadeand the transfer mechanism can readily be preset to starting or zerocondition by selectively causing a tube in each of the trigger pairs tobe made to conduct by a preset circuit.

The data represented by the combinations of on and o conditions of eachdenominational order is read out by the readout and digitrnaniiestingmeans, which includes a motor-driven sensing switch anddigit-manifesting ymeans. The manifesting means is arrested in differentdigit-manifesting positions by control means controlled by the sensingof diiferent potentials at points in a resistor network to. whichdifferent combinations of potentials are applied according to the on andolf condition of the cascaded trigger pairs, their being ten points, ofwhich onlir that point Will have a distinctive potential whichcorresponds to the digit represented by the par- The connectionsv tcularcombination of the on and off conditions of trigger pairs of thedenomination. Inasrnuch as the potentials of the points in theresistance network are derived from the cascaded trigger pairs, thecontrol means, which controls the position of the digit-manifestingmeans and the sensing switch and which has the potentials of the pointsof the network applied thereto by the sensing switch, has a compensatingmeans to insure 'against misoperation due to variations in potentialsapplied to the cascaded trigger pairs. This compensating means makes theoperation of the readout and digit manifesting means very stable andinsensitive to variations in supply potentials.

It is an object of the invention to provide an improved electronicaccounting machine having a controlled impulse-generating means forproducing strong signals to be utilized for making simultaneous entriesin desired ordersof a simplin :y

impaired when they are switched simultaneously to a plurality ofdenominational output conductors.

A further object of the invention is to provide an accumulator forcounting in the decimal notation and having, for each denomination, fourelectronic devices connected in a circuit for representing the digits ofthe notation in combinational form, the circuit being arranged to allowgreater latitude in the choice of components.

A further object of the invention is to provide a counting circuitutilizing, for each denominau tion, four electronic devices connected incascade and having improved feed-back circuits in which decouplingdevices having lower back impedance can be used.

A :further object of the invention is to provide a counting circuit madeup of four cascaded trigger pairs. each pair being operable to an oncondition and to an off condition, and utilizing the turning orf thefourth trigger pair of the cascade to on condition to send a feed-backpulse to one of the previous trigger pairs of the cascade operationthereof and utilizing the turning of the fourth trigger pair to offcondition to send a feed-back pulse to another of the previous triggerpairs of the cascade to cause an operation thereof.

A further object of the invention is to provide a means forl indicatingamounts standing inan accumulator and to provide compensating means inthe controls for the indicating means to compensate for variations involtage applied to the accumulator.

With these and incidental objects in view, the invention includescertain novel features of construction and combinations of parts, apreferred form or embodiment of which is hereinafter described withreierence to the drawings which accompany and form a part of thisspecication.

Of the drawings:

Figs. l-A and l-B together show a circuit diagram of an impulsegenerator and fthe controls therefor.

Fig. 2 shows a circuit diagram of the units denominational order of theaccumulator, including tens transfer means and the coupling devicethrough which entries can be made from the impulse generator of Figs.l-A and 1-B, and also shows digit-manifesting means for making apparentthe digit set up in the accumulator.

Fig'. 3 shows a circuit diagram of the tens denominational order of theaccumulator and the digit-manifesting means therefor but includescontrols for the coupling device through which entries can be made fromthe impulse generator of Figs. l-A and l-B and from Ithe transfer meansof Fig. 2.

In order that the invention may be explained more fully, a preferredembodiment of the invention will be described, in which descriptionvalues of potential and circuit elements, such as resistors andcapacitors, will be given and types of tubes will be specified. it isnot intended, however, to limit the invention to the embodimentdescribed nor to limit the circuit values and tube types to thosespecied, because these are merely selected as illustrative. 1t isobvious that other potentials and/or other similar tube types can beused and the circuit values of resistance and capacitance can beadjusted to maintain the proper relation between the various parts ofthe circuits. Throughout the circuit diagrams, the heater elements forthe tubes are shown conventionally.

Impulse generator The impulse generator is capable o1 generating impulsetrains containing different numbers oi impulses corresponding to thedigits of the notation in which computations are to be made, and iscapable of sending the required number of impulses over one or moreoutput conductors according to the digits desired to be entered into thevarious denominations of the accumulator. The impulse generator and itscontrols are shown in Figs. l-A and l-B.

A multi-vibrator type oscillator consisting or' tubes il and l2 (Fig.l-A) is provided to drive the impulse generator and to coordinate theoperation on the tens transfer means of the accumulator with the digitentries. These tubes have their anodes I3 and it connected over pointsl5 and l5 and resistors il" and i8, of 22,000 ohms each, to conductori9, which extends to terminal 20, to which a potential of +250 volts isapplied. The cathodes 2l and 22 of these tubes are grounded. The grid 23of tube Ilis coupled over capacitor EQ, of 50 micro-microfarads, topoint ES in the anode circuit of tube l2 and also is connected to groundover a lmegohm resistor 25. Similarly, grid 25 of tube i2 is coupledover capacitor 2, of 50 micromicrofarads, to point i5 in the anodecircuit of tube Il and also is connected to ground over resistor 23 or"1 megohm. While tubes il and I2 are shown, and function, as two separatetubes, they need not be separate but can be the two sections of a singletube such as may be purchased from Radio Corporation of America undertype designation 12AU7. With the values given, and using the 12AU7 typeof tube, the oscillator will oscillate at about 7,500 cycles per second,and points as l5 and I6 will make a like number of positive potentialexcursions.

Point i@ is coupled over a capacitor 3i) of 250 micro-microfarads togrid 3! of a driving impulse generating tube 32. Tube 32, which is shownas a separate tube but which preferably is a half of a twin triode, suchas a tube sold by Western Electric Company under the type designation2G51, is normally biased to cut-o by having its grid 3i connected over aresistor 33 of 150,000 ohms and Over conductors 34 and ,35 to terminal36, to which -30 volts is applied, and is allowed to conduct momentarilyeach time the potential of point IS becomes suiciently positive in theoperation of the oscillator to overcome the negative bias on the grid 3l.

Tube 32 has its anode 31 directly connected t the conductor 19, to which+250 volts is applied, and has its cathode 38 connected to ground by arelatively low impedance circuit including point 39 and resistor 40 of4,700 ohms.

With the values given, a positive potential impulse will be produced atpoint 30 each time tube 32 conducts momentarily, and these impulses areused to cause the sequential operation of a chain of priming tubes andto drive the impulse-trainproducing tubes.

The chain of priming tubes (Figs. l-A and l-B) utilizes gaseoustetrodes, such as tubes sold by General Electric Company under typedesignation (iL-5653, and includes a start tube and a priming tube foreach ol the digits "1 through 9.

The start tube (Fig. 1-A) has its anode 5 connected directly to an anodepotential supply conductor 45, which normally has a potential of +125volts supplied thereto from point di in the cathode circuit oi anextinguishing t8.

The control grid 50 of the start tube is normally biased to preventconduction in the tube by being connected over resistor 50, of 47,000ohms, point i, and resistor 52 of l megohm to terminal 53, to which apotential of 30 volts is applied.

The cathode 60 of the startube given a potential slightly more negativethan ground when the tube is non-conducting. rThis potential is obtainedby connecting the cathode at point 6I in a resistance-capacitancenetwork eX- tending from point G2 on conductor 03, to which a potentialof 108 volts is applied at terminal 64, over resistor S5 of 1.8megohins, point B6, resistor 67 of 1.6 megohms, point 68, resistor 69 of15,000 ohr 1s, point 6I, and resistor 70 of 22,000 ohms to ground. Point68 in this circuit is coupled to ground over a capacitor 'il of 1,000micro-microfarads. When conduction occurs in the start tube, its cathode60 will also be conductively coupled to the anode 45, and its potentialwill change from slightly negative to positive with respect to ground.

The auxiliary or shield grid 'i2 of the start tube is connected to thecathode 00 and will have the same potentials as the cathode.

The start tube is the first tube in the chain and is followed by the 9,"8, 7, 6, 5, 4, 3, 2, and l priming tubes in that order. The circuitsfor the various priming tubes are similar and will be clear from anexplanation or the circuits for the 9 priming tube (Fig. l-A

The anode 'I5 of the 9 priming tube is connected directly to the anodepotential supply conductor 46.

rihe auxiliary or shield grid 75 of the 9 priming tube is connected overresistor 'i1 of 47,000 ohms, point 18, and resistor 19, of 1 megohm, tonegative potential supply conductor 80, which is connected to terminal53 and has a potential of -30 volts applied thereto. The auxiliary grid'IS is also coupled over point 'I8 and capacitor I4 of micro-microfaradsto a driving impulse input conductor 13, which connects over point 4| topoint 39 in the cathode circuit for tube 32 and receives a positivedriving impulse of about 150 volts each time tube 32 conductsmomentarily.

The control grid 8l of the 9 priming tube is connected to point 66 inthe cathode potential supply circuit for the start tube and, with thestart tube non-conducting, has a normal negative bias sumcient toprevent the 9 prima ing tube from lbecoming conduct-ing even thoughdriving impulses are applied to the auxiliary grid. When the start tubehas been fired and is conduct-ing, the positive potential oi its cathode30 will be reflected on the potential of the control grid Sl of the 9priming tube and will reduce the negative bias t. ereon to a point wherethe tube can become conducting in response to a driving impulseimpressed on its auxiliary grid.

The cathode 82 of the 9 priming tube is supplied with potential from aresistance-capacitance network, like the one for the start tube, whichextends to ground from the negative potential supply conductor 53.

Each of the priming tubes for the digits 8 to l inclusive has an anodepotential supply circuit and a cathode potential supply circuit likethose for the 9 priming tube, each has a negative potential supplycircuit for its auxiliary or shield grid and capacitance coupling fromits auxiliary grid to the driving impulse input conductor 73, similar tothose described above in connection with the 9 priming tube, and eachhas its cont-rol grid connected to the cathode potential supply circuitof the preceding tube in the chain to be primed thereby upon conductionoccurring in the preceding tube.

It is to be noted that the driving impulses from tube 32 are noteiective to cause an unprimed tube to conduct; onsequently the impulseswill be ineffective on any of the priming tubes of chain until theSt-art tube has been and primes the 9 priming tube. The start tube isiired in the following manner. Point 5i in the control grid circuit forthe start tube is coupled over conductor 85, capacitor of l0micro-microfarads, and point 8'! to the motor bar or start key switch88, which is normally open but which can be closed to connect point 0lto conductor 39, which extends to terminal 00, to which a potential of+250 volts is applied. When the motor bar or start key switch B isclosed and the +250 volts is applied to capacitor 85, a positive impulsewill be impressed on the control grid 49, which impulse is suihcient tolire the start tube, thereby priming or conditioning the 9 priming tubeso that it can respond and be fired by the next driving impulse onconductor '13. Point 87in the motor bar or start key control circuit isconnected to ground over resistor of 47,000 ohms to provide a dischargepath through which capacitor 8B can be discharged when the motor bar orstart key switch 88 is opened.

Each oi' the priming tubes, when, red, will prime the next tube of thechain, so that it will be fired by the next driving impulse.Accordingly, after the start tube has been fired by the closing of thestart key switch 80, the next nine driving impulses will fire the tubesof the priming chain one after another.

The tubes of the chain, being gas tubes, will remain conducting, oncethey are fired, until they are extinguished by the operation of anextinguishing means which includes the tube 4S. This operation of theextinguishing means takes place after the last tube in the chain hasbeen red and has effected its control, at which time all the tubes ofthe chain are rendered non-conducting.

Since the priming tubes oi the chain are lred in sequence by successivedriving impulses and are all extinguished at the same time, the severaltubes will be conducting for progressively longer periods of time; thatis, the 9 priming A:2G51 type of tube.

tube will be conducting longer than the 8 tube, the 8 tube will beconducting longer than the "7 tube, etc.

Each priming tube controls a related impulsetrain-producing tube bypriming that tube as long as the priming tube is conducting, and enablesthe driving impulses from tube 32, which are impressed continuously onthe impulse-trainproducing tubes, to become eiective to operate the tubeand produce a train of impulses corresponding in number to the digit towhich the priming tube is related. For example, theimpulse-train-p-roducing tube related to the 9 priming tube will producea train containing nine impulses, the imp-ulsetrain-producing tube whichis related to the 8 priming tube will produce a train of eight impulses,etc., the impulse-train-producing tube related to the l priming tubeproducing one impulse.

The circuits and controls for the-impulsetrain-producing tubes aresimilar, and it is believed that an understanding of the operation ofall these tubes will be clear from a description of the operation of oneof them.

The impulse-train-produ-cing tube for producing a train of nine impulsesis representative and is shown at in Fig. l-A. This tube is shown as aseparate triode, but preferably it is one half of a twin triode, such asthe above-mentioned The tube has its anode |0| connected directly toconductoni, which, as explained earlier herein, has a potential of +259volts applied thereto at terminal 20. The cathode |02 of the tube isconnected over point |03 and resistor |00 of 2,200 ohms to point |05 onpotential supply conductor |00, which has a potential of +130 voltsapplied thereto at terminal |01. This anode-cathode potential supplycircuit has a very low impedance and will produce a strong positiveimpulse of about 55 volts at point |03 each time the tube |00 isoperated.

Control grid |09 of tube |00 is connected over point H0 and resistor of100,000 ohms to point ||2 in the cathode potential supply circuit forthe "9 priming tube. Point ||0 in the grid circuit is also coupled overa capacitor ||3 of 250 micro-micrcfarads to the driving impulse inputconductor H0, which is connected over point 4| to point 39 in thecircuit of the driving impulse generating tube 32. is not conducting,point l2 in its cathode circuit and consequently grid |09 of theimpulsetrain-producing tube |00 will be slightly negative with respectto ground, and, since the cathode |02 is at a potential of +130 volts,the tube |00 will be biased suiciently past cut-off that the drivingimpulses on conductor HZ will be ineffective to cause conduction in tube|00.v However, when the "9 priming tube is conducting and its cathodehas become positive, point |I2 willbecome more positive and reduce thebias on tube |00 to a point where the driving impulses on conductor H0will be effective to cause momentary conduction in the tube |00 andthereby provide positive impulses at point |03. Capacitor H5,

which is similar to capacitor 'H in the cathode' cir-cuit of the starttube, delays the application of the priming potential to grid |09suiciently that the impulse which fires the "9 priming tube will havepassed before the tube |00 is ready for operation. The iirst drivingimpulse that will be effective on tube |00 will be the same one that resthe 8 priming tube.

Conductor is connected to point |03 and will have the positive impulsesat point |03 im- Whenthe 9 priming tube pressed thereon. Switch |2 I,which can be closed by a 9 digit key or any other switch-operatingdevice in the units denominational order, will connect the conductor |20to a units denominational output conductor |22. Similarly, a switch |23can be closed by a 9 digit or other switchoperating device in the tensdenominational order to connect the conductor |20 to a tensdenorninational output conductor |24. While only two sets of switchesand two denominational output conductors have been shown, it is obviousthat as many can be provided as are needed according to thedenominational capacity desired.

Each of the other impulse-train-producing tubes has connections similarto the ones given above and is capable of producing the required numberof impulses which can be switched to output conductors |22 and |24 asdesired. The use of the low impedance source of impulses allows theimpulses to be switched to a plurality of output conductors withoutimpairing the ability of the impulses to operate the accumulator.

The driving impulse, which follows the driving impulse which res the "1priming tube, Will be effective on the primed impulse-train-producingtubes to cause the last impulse in each train to be generated and willbe effective on the primed tube |00 (Fig. l-B) to cause that tube tooperate and generate the impulse for eiecting an entry of the digit l inthe accumulator. This impulse which is generated by the tube |00 goesout over conductor |05, from which it can be switched to outputconductors, as |22 and |24. The impulse on conductor |05 also is used toopferat-e the extinguishing means to cause the tubes of the chain to beextinguishedand remove the priming from the impulse-train-producingtubes.

As explained earlier herein, the anodes of the start tube and thepriming tubes l to 9 are connected to conductor 00. The potential ofconductor t0 is derived from an impedance network having one branchwhich extends from point on -l-voltconductor 03, over resistor |5| of56,000 ohms, point |52, and to ground over resistor |53 of 500,000 ohms,and having another branch which extends from point |52, over point 0l,to the cathode |54 of the eX- tinguishing tube 00, and through the tubewhose anode |55 is directly connected to conductor 89, to which apotential of +250 volts is applied. IIube 48 is preferably of the typesold by Radio Corporation of America under the type designation 6AQ5,and, by varying the impedance thereof, the potential applied toconductor 06 and the anodes of the tubes of the chain can be controlled.

Normally, the potential on the control grid |55 ci tube 40 is such thatthe tube will conduct suiliciently to give its cathode |50 and theconductor 06 a potential of +125 volts. However, when the potential onthe grid |55 of tube 00 is modified to increase the impedance of thetube so that less current flows therethrough, the cathode potential andthat of conductor it will become less positive and even may becomenegative with respect to ground, thereby causing the anode potential ofthe conducting tubes of the chain to drop below their cathode potentialand the tubes to be eX- tinguished.

The potential of grid |50 is controlled from a resistor |00 in the anodecircuit of a twin triode control tube |011, which is preferably of thetype sold by Radio Corporation of America under the type designation12AX'7. The anodes |02 and |63 :are connected together and over theresistor 9 |60 of 470,000 ohms to conductor 00, to which a potential of+250 volts is applied.

The cathode of one of the triodes of tube |6| is connected directly toterminal |05 and has a potential of +65 volts applied thereto. Thecathode |50 of the other triode of tube |0| is connected directly toterminal |01, to which a potential of 08 volts is applied.

Grid |10 cooperates with the anode |03 and the cathode |04 to determinethe normal potential applied to grid |50 of tube 4S. Grid |10 issupplied with the required potential from an adjustable tap |1| onresistor |53.

Grid |12 cooperates with the anode |02 and the cathode |00 of tube |6|and is effective therethrough to modify the potential of grid |50` ofextinguishing tube 48 to.increase the impedance of this tube and causethe extinguishing of the tubes of the chain.

The impulse which is generated by tube |40 and is applied to conductor|45 is impressed on grid |.2, either directly or through animpulsewidening device, and will cause the extinguishing of the tubes ofthe.. chain. In the disclosed embodiment, the impulse on conductor |45will be applied through an impulse-Widening device. conductor |45 iscoupled through a capacitor |15 of .005 niicrofarad to the anode |15 ofa diode |11. Preferably this diode is one half of a twin diode tube ofthe type sold by Radio Corporation of America under the type designationGAL-5. Anode |16 of the diode |11 is also connected over resistor |18 of39,000 ohms and conductor |10 to conductor 03, which has a potential of108 volts applied thereto. Cathode |80 of the diode is also connected toconductor |10 over a resistor |8| of 1 megohm in parallel with acapacitor |02 of 250 micro-microfarads. Point |83 in this circuit isconnected over resistor |84 of 200,000 ohms to the grid |12 of thecontrol tube.

A positive impulse on conductor |45 will be effective, through the lowimpedance of the diode |11, to charge capacitor |02 and make point |33and the grid |12 connected thereto more positive. Since the dischargepaths for the capacitor |82 are through the resistor |8| of l megohm andthe high back impedance of the diode 11, the grid |12 will remainpositive for a longer time than that required for the impulse onconductor E45.

When grid |12 becomes more positive and more current ows throughresistor |50, grid |50 will become more negative and increase theimpedance of tube 40, thereby to reduce the anode potential applied tothe tubes of the chain sufficiently to cause them to be extinguished.

The impulse-widening means, 'while not necessary, provides an additionalfactor of safety in the operation of the device, because it allows theanode potential for the tubes of the chain to be depressed for a longerperiod of time than ref' quired to deionize them and insures that alltubes of the chain will be extinguished.

Accordingly, for each operation of the tart tube,impulse-train-producing tube |00 will produce a train of nine impulseson conductor |20; tube 30 will produce a train of eight impulses onconductor |3|; tube |52 will produce a train of seven impulses onconductor |33 tube 04 will produce a train of six impulses on conductor|35; tube |30 will produce a train of ve impulses on conductor 131; tube|38 will produce a train of four impulses on conductor |30; tube |00will produce a train of three impulses on conductor v14| tube |02 willproduce a train of two impulses on conductor |43; and tube |44 willproduce an 10 impulse on conductor |45. Each impulse train is common tothe plurality of denominational output conductors, and the trains ofimpulses can be switched to the output conductors according to thedigits desired to be entered into the various denominations of theaccumulator.

If no entry is to be made in any denominational order of theaccumulator, a zero switch, as 45, for that order is closed to connectthe related output conductor to conductor |05 over a resistor |01 of2,200 ohms to provide a comparable low impedance loading for the outputconductor when it is not otherwise connected to animpulse-trainproducing tube.

It should be noted that the start tube and its controls will allow onlyone impulse-trainpr-oducing operation of tubes |00, |30, |32, |34, etc.,for each closure of the motor bar or key switch 08, because, as long asthe switch remains closed, capacitor will remain charged, and noadditional firing impulses can be applied to the control grid 49 of thestart tube.

The impulse generator also includes a transfer-effectingimpulse-generating means which is controlled from the oscillator and istimed to cause transfer entries to be made without interference withdigit entries in the accumulator.

The transfer-effecting impulse-generating tube 00 (Fig. l-A), whichpreferably is one half of the above-noted 12AU7 type of tube, has itsanode i0: connected over point |02 and resistor |93 of 22,000 ohms toconductor l0, to which is applied a potential ci +250 volts, and has itscathode |013 directly connected to ground. Control grid 505 normallybiases the tube to cut-off by being connected over resistor |06, point|01, and resistor |00 to conductor 35, to which a potential of -30 voltsis applied at terminal 36. Control grid |05 is also coupled from point|91 over capacitor |09 ration of the oscillator.

Whenever the tube conducts, a negative potential drop of about voltsoccurs at point |02 in its anode circuit, and these potential drops areapplied over conductor 200 (Figs. l-A and l-B) and resistor 20| of47,000 ohms to the transfer means of the units denominational order ofthe accumulator and over resistor 202 of 47,000 ohms to the transfermeans of the tens denominational order of the accumulator. The negativeimpulses which are impressed on conductor 200 will occur' during theintervals between the positive impulses on Bthe denominational outputconductors |22 and |24 and are effective to cause transfer entries to bemade in the accumulator without interfering with the digit entries. Themanner in which the transfer-effecting impulses cause the operati-on ofthe tens transfer means will be explained more fully hereinafter.

Accumulator Two denominational orders of the accumulator are shown inFigs. 2 and 3.

Each denominational order includes an electronic coupling device, anelectronic tens transfer means, and a plurality of interrelatedelectronic devices capable of accumulating in the decimal notati-on andrepresenting, in combinationai form, the units digit of saidaccumulation.

Fig. 2 shows the units denominational order of the accumulator.

rThe coupling device is shown as a twin triode,

tube 220, preferably of the above-noted 2G51, type, though, as willappear later, only one of the tri-odes is utilized in the units order,the one for coupling the order of the accumulator to the correspondingdenominational output conductor of the impulse generator. In theembodiment shown, there are no tens transfer entries to be made in theunits denominational order of the accumulator, and accordingly the otherof the triodes is not used to control entries therein.

Tube 220 has both of its anodes 22| and 222 connected together and overpoint 223 and resistor 224 of 47,000 ohms to conductor 225, to which apotential of +250 volts is applied at terminal 226, and has its cathodes221 and 223 and shield 2|9 grounded.

Grids 230 and 23| have biasing potential supplied thereto from a biasingpotential supply circuit which extends to ground from conductor 232, towhich a potential of 75 volts is applied at terminal 233, over resistor234 of 100,000 ohms and resistor '235 of 47,000 ohms, grid 230 beingconnected over point 236, and resistor 231 of 47,000 ohms to point 230in the bias potential supply circuit and grid v23| being likewiseconnected over a resistor 240 of 47,000 ohms to point 24| in the biaspotential supply circuit. Point 24| is connected to ground over astabilizing capacitor 242 of 500 micro-microfarads. The potentialsupplied to the grids normally biases both halves of the tube tocut-off.

The units denominational output conductor |22 (Figs. l-A, l-B, and 2) ofthe impulse gen erator is coupled over capacitor 243 of 250micromicrofarads to grid 230, which controls conduction between anode22| and cathode 221 of the left triode in the tube l220. Whenever animpulse of an impulse train is impressed on conductor |22, it will beeffective to cause the triode, which is controlled by grid 230, toconduct and produce a potential drop at point 223 due to resistor 224 inits anode circuit.

In the units denomination of the disclosed embodiment of theaccumulator, grid 23|, which controls the right-hand triode of the tube220, will have no impulses applied thereto, so this triode of the tubewill remain biased to cut-off.

The potential drops which are produced at point 223 when conductionoccurs in the tube are used to provide negative impulses to operate theinterrelated devices of this denominational order for accumulatingamounts. The interrelated devices consist of four trigger pairsconnected in cascade and with selective feed-back circuits to enablethem to accumulate values in the decimal notation and to represent thevarious digits of the notation by diierent combinations of on or offconditions of the trigger pairs.

As is well known, an electronic device known as'a trigger pair consistsof a pair of electron discharge tubes having interconnectionstherebetween to control their operation so that, at any given time, oneof the tubes is conducting. and the other tube is non-conducting, andthe act of changing the conducting condition of one of the tubes willcause the conducting condition of theother of the tubes of the pair tochange. With the circuit constants to be given herein, the 'triggerpairs' will be relatively insensitive to positive impulses but willrespond to negative impulses, so that a negative input impulse apy maybe made up of two separate tubes; however, in order to provide a morecompact device, each of the cascaded trigger pairs in the disclosedembodiment of the invention is formed by interconnecting the two halvesof a twin triode type of tube, preferably of the aforementioned 2G51type.

The first trigger pair of the cascade will be that marked A, the secondtrigger pair will be B, the third trigger pair will be C, and the fourthand rlnal trigger pair of the cascade will be D. The trigger pairs willbe considered in their on `condition when the left triode of the triggerpair is conducting and in their off condition when the left triode ofthe trigger pair is in non-conducting condition. The manner in which thetrigger pairs represent the various digits can be seen from thefollowing table, in which "O designates the oir condition and Xdesignates the on condition of a trigger pair.

| Digit A B l o D X o o X o o o X o o X o X X O X X o o X X o X X X X XX X X Trigger pair A is the first trigger pair of the cascade and isoperated by impulses impressed thereon from the coupling device, tube220. The left triode 245 of the trigger pair has its anode 246 connectedover resistor 241 of 47,000 ohms to the +250-volt conductor 225 and hasits cathode 248 connected directly to ground. Similarly, the righttriode 250 of the trigger pair has its anode 25| connected over resistor252 of 47,000 ohms to the +250-volt conductor 225 and has its cathode253 directly connected to ground.

Grid 255 of the left triode 245 is connected to a negative bias supplyover point 256, resistor 251 of 150,000 ohms, `and conductor 232, towhich a potential of volts is applied at terminal 233, and also iscoupled to the anode 25| of the right triode 250 over a networkcontaining resistor 258 of 200,000 ohms shunted by resistor 250 of ohmsin series with capacitor 260 of micro-microfarads. In a similar manner,the grid 263 of the right triode 250 is connected to the negative biassupply over point 264 and resistor 265 of 150,000 ohms to conductor 260,

" which is connected over a reset switch 261 to conductor 232. Grid 263is also coupled to the anode 246 of the left triode 245 over a networkcontaining resistor 268 of 200,000 ohms shunted by resistor 269 of 100ohms in series with capacitor 210 of 150 micro-microfarads.

Points 256 and 264 in the bias supply circuits for the grids 255 and 263are coupled, respectively, over capacitors 215 and 216 of 25micromicrofarads to a conductor 211, thence over resistor 218 of 47,000ohms to the point 223 in the anode circuit of the coupling device, tube220.

With the circuit constants given, trigger pair A will be responsive tonegative impulses and will reverse the conducting status of the triodestherein each time a negative impulse is impressed on the grids of thetriodes. Accordingly, the trigger pair will reverse its conductingstatus each time the coupling device responds to an impulse from theimpulse generator and sends a negative impulse to the pair.

Trigger pa-ir B, which is the second trigger pair of the cascade, isoperated to reverse the conductive condition of the triodes therein inresponse to an impulse impressed thereon from trigger pair A when thatpair goes from its on condition to its 01T condition. Trigger pair B isalso operated from its oli condition to its on condition in response toa feed-back irnpulse from trigger pair D in a manner to be explainedmore fully hereinafter. The anodes 200 and 201, respectively, of theleft triode 282 and the right triode 203 of this pair are connected overresistors 204, and 285 of 47,000 ohms, respectively, to the |25Gvoltconductor 225, and the cathodes are connected to ground.

Grid 286 of the left tiode 282 is connected to negative bias supply bybeing connected over point 281 and resistor S of 150,000 ohms toconductor 256, and is also coupled to the anode 28! of the right triode233 over a network containing resistor 200 of 200,000 ohms shunted byresistor 29| of 100 ohms in series with capacitor 292 of 250micro-microfarads. Grid 205 of the right triode 233 is connected to thenegative cias supply over resistor 2.35 of 47,000 ohms, point 291,resistor 203, of 150,000 oliros, and conductor 26S. Grid 205 is alsocoupled to the anode 280 of the left triode 282 over resistor 200 andresistor 299 of 200,000 ohms, resistor 200 being shunted by resistor 300of 100 ohms in series with a capacitor 30! of 250 micro-microfarads.

' Point 237 in the bias supply circuit to grid 280 is connected overresistor 301i or 47,000 ohms and capacitor 305 of rnicio-niicroiarads toconduetor 300, which extends to the anode 255 of the right triode 250 oftrigger pair A. Point 20T in the plas supply circuit for grid 205 isalso coupled to conductor over a capacitor 301 of 25 micro-microiarads.Each time tri ger pair A is operated to its oil condition and the righttriode '2E-0 thereof conducts, a negative impulse will 'ce sent overcapacitors 04 and 301 to the grids 285 and 205 of the trigger pair B tocause a reversal of the conducting condition of the triodes therein.

Resistors 200 and d are isolation resistors, which are operative tocontrol the effect of the feed-baci: impulse on trigger pair B and alsocooperate With the rectier in the feed-hack circuit to enable rectiersof the semi-conductor or barrier-layer type lia-ying lower backimpedance to be used and still prevent impulses from trigger pair B fromcausing improper operation of trigger pair D. The manner in which theseresistors are operable to perform the alcove functions will be explainedmore fully hereinafter, when the feed-baclt circuit and its operationare explained.

Trigger pair C, which is the third trigger pair of the cascade, isoperated to reverse 'the conducting condition ot the triodestherein inresponse to an impulse from trigger pair B when that pair goes irorn itson condition to its "oii condition. Trigger pair C is also operated fromits cil condition to its on condition in response to a feed-back impulsefrom trigger pair D in manner to ce explained more fully hereinafter.The circuit arangeinent and circuit constants for trigger pair C areidentical Wit-h t-liose of trigger pair ES will not ce repeated.

Trigger pair which is the last trigger pair in the cascade, is operatedby inipulses impressed 'i thereon from trigger pair C and is effectiveto send feed-back impulses selectively to trigger pairs B and C and tosend an impulse to a tens transfer means to prepare it for a tenstransfer operation.

The left triode Sie of trigger pair D has its anode 3H connected overpoint 3i2, resistor 3i3 of 22,000 ohms, point Shi, and resistor SES of22,000 ohms to the +250-volt conductor 225 and has its cathode connectedto ground. in a like manner, the right triode 2HE has its anode 3Hconnected over point Sii, resistor tie of 22,000 olinis, point 320, andresistor 0.2i or 22,000 ohms to the -{-250volt conductor 225, and hasits cathode connected to ground.

Grid 325 of the left triode 2li? is connected to the negative biassupply over point 320, resistor 32"! of 150,000 ohms, and conductor 232,and is also coupled to the anode Si? of the right triode 3|?) overresistor 320 00200000 onins, shunted cy resistor oi ohms in series withcapacitor of 250 micro-microiarads. Similarly, the grid 335 of the righttriode dit is connected to the negative bias supply over point 335,resistor 33"! or" 150,000 ohms, and conductor 20?. Grid 335 is alsocoupled to the anode 3H oi the left triode Sill over resistor 333 of200,000 ohms, shunted by resistor 339 of 100 ohms in series withcapacitor 300 of 250 inicro-1nicrofarads- Points 320 and 330 in the olaspotential supply circuits ci grids and 335, respectively, are coupledover capacitors 3M and 302 of 25 micromicrofarads to conductor whichextends to the anode of the right triade of trigger pair C and enables anegative impulse to he impressed on the grids 325 and each time triggerpair C turns from its on condition to its ofi condition.

A feed-pack circuit extends from point- 320 in the anode circuit for theright triode @it of trigger pair D, over capacitor 305 ofmicrornicrofarads, 3&0, rectifier 3M, which is, tor example, a germaniumcrystal diode of the type sold by Western Electric Company under thetype designation Vv'ElOB, and conductor 43 to the grid 205 of the righttriode 283 of the trigger pair B. The rectifier 3M is oriented to passnegative feed-sack pulses from the trigger pair D to the trigger pair Band to prevent negative impulses en grid from being transmitted totrigger pair i3. Point 3130 in. the feed-back circuit is connected toground over a resistor 312.9 of ll'l0,000 olinis to provide a leakagepath to discharge capacitor 305.

The above feed-back circuit and its related circooperate in thefollowing manner to malte it possible to use crystal diodes instead ofvacuum tube diodes in the feed-back circuit. In the circuit arrangementshown, the feed-back impulse is applied directly to grid 205, and theisolation resistors 220 and 304 are in series between the feed-hack c`1cuit and grid 285 ci the leit tricde 282. These resistors reducematerially the eiect of the negative feed-baci: impulse on grid 20E andthe triode 202 controlled thereby. By thus attenuating the eect of thereed-back impulse on the left triode, the eiiect of the potentialcna-nge of anode will be greater and a smaller-ainplitu-:ie feed-baci:impulse applied directly to the grid 235 of the right tiiode Will be aserective to reverse the operation of the pair as t .e largeamplitudeimpulse applied in common to the triodes of the pair from the precedingtrigger pair of the cascade. This enables the feed-back impulse to betaken from the midpoint of the resistance in the anode circuit for theright triode 310 of trigger pair D, at point 320, instead of l5 directlyfrom the anode at point BIB. With the feed-back impulse taken from point32! by connecting the feed-baci: circuit thereto, resistor 3|!) isplaced in series between the feed-back circuit and the anode Sil of thetriode 3dB and attenuates the eect on anode Eli and grid 325, coupledthereto, of any impulses transmitted from trigger pair B. Similarly,resistor 295 in the circuit to grid 2s?) of the right triode of triggerpair B will attenuate impulses applied to the grid 295 from anode 2.8i!of the left triode 282 of trigger pair B, and also from anode 25| ofright triode 258 of trigger pair A, and, consequently, will attenuatethe effect of impulses from these sources on the feed-back circuit,which is connected directly to grid 2&5. The above attenuating effectsof resistors 295 and 359 are cumulative and are effective in thecircuitarrangement to enable crystal rectiers of the semi-conductor orbar rier-layer type, which can be much smaller but which have lower backresistance than vacuum tuberectiflers, to be used in the feed-backcircuit without causing improper operations to take place.

A similar feed-back circuit extends from the midpoint Si i of the anoderesistance network for the left triode 350 of trigger pair D, overcapacitor 355 and rectiiiers 35B, to the grid of the right triode oftrigger` pair C, and enables the turning of trigger pair D on to send anegative feed back impulse to trigger pair C to turn it from Lo Ion-!The manner in which the various trigger pairs are operated incombinations to represent digits of the decimal notation will now beexplained in an operation in which ten impulses are sent to thedenomination to operate it through a complete cycle and return it tostarting condition. As shown in the tabulation given earlier herein, thezero or starting condition of the trigger pairs of the denomination isthat in which trigger pairs A, C, and D are in off condition, With theirright triodes conducting, and trigger pair B is in its on condition,with its left triode conducting. All input impulses to the denominationare applied to the coupling device, tube 220, which in turn applies themto trigger pair A, the first trigger pair of the cascade.

The rst impulse applied to trigger pair A changes it from its orfcondition to its on condition, so that the trigger pairs A and B will beon and trigger pairs C and D will be off to represent the digit "1.

The second impulse applied te trigger pair A changes it from on to oliAs trigger pair A goes from on to oli it sends an impulse to triggerpair B, which turns trigger pair B from on to oi and triggerv pair B, ingoing from on to oii`, sends an impulse to trigger pair C to turn itfrom off to onf At the end of this entry, trigger pairs A, B, and D areoi and trigger pair C is on to represent the digit2.

The third impulse applied to trigger pair A merely changes that pairfrom ei' to en At the end of this entry, trigger pairs A and C are onand trigger pairs B and D are foi to represent the digit 3.

The fourth impulse applied to trigger pair A turns trigger pair A fromon to off and trigger pair A, in turning oi sends an impulse totriggerpair B to turn it from off to on. At the end of this entry,trigger pairs A and D are 01T and trigger pairs B and C are on torepresent the digit 4.

16 The fifth impulse applied to trigger pair A merely turns this triggerpair from off to 011, and, at the end of this entry, trigger pairs A, B.and C will be on and trigger pair D will be oif" to represent the digit5.

The sixth impulse applied to trigger pair A will turn this trigger pairfrom on to oi and,

in turning from on to oii trigger pair A will send an impulse to triggerpair B to turn it from on" to olii The turning of trigger pair B to oiiwill send an impulse to trigger' pair C to turn it from on to Off, andtrigger pail' C, in turning to ofi Will in turn send an impulse totrigger pair D to turn it from oi to 011. When the trigger pair D isturned from off to on, a feed-back impulse is sent from the left triodeof trigger pair D to the right triode of trigger pair C to cause triggerpair C to be turned on. At the end of this operation, trigger pairs Aand B will be off, and trigger pairs C and D will be on to represent thedigit 6.

The seventh impulse applied to trigger pair A will merely turn triggerpair A from off to on," and, at the end of this entry, trigger pairs A,C, and D will be on and trigger pair B will be orf to represent thedigit 7.

The eighth impulse applied to trigger pair A will turn trigger pair Afrom on to off, and the turning of trigger pair A ofi sends an impulseto trigger pair B to turn trigger pair B from off to on. At the end ofthis entry, trigger pairs B, C, and D will be on, andY trigger pair Awill be oli to represent the digit 8.

The ninth impulse applied to trigger pair A will merely turn triggerpair A from oli to 011, so that, at the end of this entry, all thetrigger pairs will be on to represent the digit 9.

The tenth impulse which is applied to trigger pair A will turn triggerpair A from its on condition to its off condition, and trigger pair A,in turning to its off condition, will send an impulse to trigger pair Bto turn it from on to offf Trigger pair B, in turning to its "oifcondition, will send an impulse to trigger pair C to turn it from on toofi and trigger pair C, in turning ofi'j Will send an impulse to triggerpair D to turn it from on to oft As trigger pair D is turned from on tooff, the other feed-back circuit becomes effective, and an impulse issent from the right triode SIS thereof to the grid 295 of the righttriode of trigger pair B to turn the trigger pair B from oi to on." Atthe end of this entry, the trigger pairs A, C, and D will be in oficondition, and trigger pair B will be in on condition, which is thecondition in which they were at the beginning of the entry of the tenimpulses.

It is seen, therefore, that the cascaded trigger pairs of thedenomination can be operated in combinations of on and off conditions torep# resent the digits 1 to 9 and 0, and can be returned to startingcondition upon the application of ten impulses to the rst trigger pairof the cascade.

Fig. 3 sho-ws the coupling device, the cascaded trigger pairs A, B, C,and D, and the tens transfer means of the tens denominational order ofthe accumulator. The tens denominational order is representative of allintermediate orders of the accumulator. The highest denominational orderof the accumulator would be the same as the intermediate orders exceptthat it would not be required to control a transfer means to transfervalues to a higher order. Except for an additional control of thecoupling device by which 17 tens transfer entries can be made from alower order, the circuits of this figure are the same as those for theunits denominational order shown in Fig. 2. Where the circuit constantsand circuits of Fig. 3 are the same as those of Fig. 2, the descriptionof them will not be repeated.

The coupling device for the tens denominational order is a twin triode360 (Fig 3), similar to the twin triode 220 (Fig. 2). As is the casewith the coupling device in Fig. 2, the anodes 36| and 362 (Fig. 3) areconnected together and over a resistor 363 of 47,000 ohms to a +250-voltconductor 364, and the cathodes are connected to ground. Grid 365 of theleft triode is supplied with negative grid bias from conductor 366, towhich -75 volts is applied, and is coupled over capacitor 361, of 250micromicrofarads, to the tens denominational output conductor |24 of theimpulse generator (Figs. 1 and'l-A). The left triode is normally biasedto cut-01T but will conduct momentarily when the positive outputimpulses from the impulse generator are applied to grid 365. Each timethis triode conducts, the drop across the anode resistor 363 Will causea negative impulsel to be applied to the first trigger pair of thecascade to cause an advance in the digit represented vby the operatingcondition of the cascaded trigger pairs.

*Grid 310 of the right triode of the coupling device is supplied withnegative biasing potential from conductor 366 and is coupled overcapacitor 31|, of 250 micro-microfarads, to conductor 312, which extendsto the transfer means. of the next lower order and receives a positiveimpulse each time a transfer entry is made from the lower order. Eachpositive transfer impulse which is applied to grid 310 will cause theright triode of the coupling device to conduct momentarily, whichconduction will produce a drop across the anode resistor 363 similar tothe one produced .by an impulse from the impulse generator. This drop isapplied as a negative impulse to the first trigger pair of the cascadeto cause a unit advance in the digit representation of the cascadedtrigger pairs.

Tens transfer means Tens transfer means are provided for the accumulatorto make an entry of a value of one inthe next higher order of theaccumulator each time an order exceeds its capacity. Since the same typeof transfer means couples adjacent denominational orders of theaccumulator, the operation of the various transfer means will be clearfrom a description of the operation of the means coupling the units andtens denominational orders of the accumulator.

, The transfer means includes a trigger` pair which is operated from anormal' conducting condition when the related denominational cascadedtrigger pairs exceed their digitalcapacity and is effective to cause -anentry in the next higher order when restored to normal condition.

The tens transfer trigger pair (Fig. 2) is shown as being made up of twohalves of a twin triode,1tube 315, preferably of the above-mentioned2C51 type.

:Anodes316 and 311 of 'the left and right triodes of this trigger pairare connected, re spectively, over resistors 318 and 319 of 47,000ohmsto the +250-volt conductor 225, and the cathodes of these triodesare connected to ground.

Grid 380 of the leftvtriode is coupled to the negative `bias supplyconductor 232 over-point .Vil

38| and resistor 382 of 150,000 ohms and also is coupled to anode 311 ofthe right triode by the trigger connection including resistor 383 of200,000 ohms, shunted by resistor 394 of 100 ohms in series withcapacitor 335 of 250 micro-microfarads. In a corresponding manner, grid386 of the right triode is coupled to the negative bias supply conductor266 over point 394 and resistor 381 of 150,000 ohms and also is coupledto anode 316 of the left triode by the trigger connection includingresistor 388 of 200,000 ohms, shunted by resistor 389 of 100 ohms inseries with capacitor 390 of 250 micro-micro farads. When theaccumulator is initially setin op` eration or is reset to zero, the tenstransfer trigger pair is set in its normal condition, With the righttriode conducting, as will be explained more fully hereinafter when theresetting operation is considered.

When a tens transfer is required, the cascaded trigger pairs of thedenomination will cause the tens transfer trigger pair to operate toreverse itsconducting status. This is accomplished in the followingmanner. As is seenfrom the tabu.-

' lation given earlier herein, the trigger pair D will change fromitscn'condition to its off condition only when the digit represented bythe cascaded trigger pairs changes from 9 to 0. The drop across anoderesistors 3|8 and 32| of the right triode of this trigger pair whichoccurs when the pair changes from on to oif is applied as a negativeimpulse to grid 386 of the right triodeV of the tens transfer triggerpair, over conductor 39|, resistor 392 of 47,000 ohms, capacitor 393 of25 micro-microfarads, and point 394, and Will cause the tens transfertrigger pair to be operated from its normal condition and reverse theconducting statusof its triodes.

As explained earlier herein in connection with the impulse generator,the transfer-effecting impulse-generating Atube |90 (Fig. l-A) is drivenfrom theoscillator and produces negative potential drops which aretransmitted over conductor 200 and resistors, as 20| and 202, during theintervals between the occurrence of positive impulses on thedenominational output conductors. as |22 and |24.

The drop transmitted over resistor 20| is transmitted further overconductor 395 (Figs. 1-B and 2), capacitor 396 of 25 micro-microfarads,and point 38| and is impressed as a negative impulse ongrid 380 oftheleft triode to cause the trigger pair to reverse its conductingstatus andreturn to its normal condition if it had been operated fromnormal condition by a required tens transfer. If the tens transfertrigger pair is in its normal condition, theleft triode Will already bein non-conducting condition, and the negative transfer-effectingimpulses applied to grid v380 will not have any effect on the triggerpair to change the status of conduction of its triodes; but. if thetrigger pair has been changed from normal condition due to a requiredtens carry, then the left triode will be conducting and the negativetransfer-effecting impulse will render the left triode non-conducting,and, through the trigger action, Will restore the pair to its normalcondition. As the left triode becomes non-conducting., its anodepotential becomes more positive, and this potential change istransmitted over conductor 400, resistor 40| of 47,000 ohms, conductor312 (Figs. 2 and 3), and capacitor 31| to the grid 310 in the righttriode of the coupling device. tube 360, of the tens denominationalorder .to

cause an impulse to be impressed on the cascaded trigger pairs of thetens denominational order to make a unit entry therein.

It is to be noted that, since the transfer entries are effected byimpulses which are generated in the intervals between the times whendigit-entryeffecting impulses can be generated, transfer entries can bemade at any time during or after a digit entry without interfering withthe digit entry.

The tens transfer` means, which is controlled from the tensdenominational order trigger pair D (Fig. 3), includes the twin triode402, which has transfer-effecting impulses applied thereto from theimpulse generator over conductor 200, resistor 202, conductor 403 (Figs.l-B and 3) and capacitor 404, and which can send a tens transfer signalover resistor 405 and conductor 406 to the next higher or hundreds orderof the accumulator when required.

In a similar manner, other transfer means can be controlled from thetrigger pairs D of their related orders and can be operated bytransfereiecting impulses to cause tens transfer entries to be made inappropriate higher orders.

Resetting In order to 'prepare the accumulator initially to receiveentries or to reset it to its zero condition, reset switches, as 261 inFig.. 2 and 4|0 in Fig. 3, are provided in the negative bias supplycircuits for the grids of the right triodes of triggerjpairs A, C, and Dand the left triode of trigger pair. B. Momentary opening of theswitches will remove negative bias potential from these grids and Willcause the trigger pairs A, C, and D to be set in their off condition andtrigger pair B to its on condition.

While separate reset switches as 261 and 4|0 are shown for variousdenominations, it is obvious that conductors, as 266, for the variousdenominations could be connected together and over a single Yresetswitch to a source of -75 volts.

The transfer trigger pairs are also conditioned bythe operation of thereset switches, which remove ne'gative bias from the grids of the righttriodes of these trigger pairs and cause these trigger pairs to be setto their normal position, with the right triode conducting. This controlof the transfer trigger pairs from the reset switches insures that thesetrigger pairs will always be setito ,their normal'condition initially orafter a resetting operation, and prevents any improper transfers frombeing made as a result of changing trigger pair D to its 01Tcondition'in the initial setting or resetting operations.

Digit-manifesting means vMeans are provided to manifest the digit valuesrepresented by the combinations of on and oir conditions of the cascadedtrigger pairs of the various denominational orders of the accumulator.

The manifesting means for each of the denominational orders aresubstantially the same, thatfor thev units denominational orderincluding a digit-manifesting wheel 4| (Fig. 2), a readoutscanningswitch 4|2, and a notched element 4|3. which can rotate together andwhich are driven by a friction drive, shown diagrammatically at 4| 4,until arrested by a stop pawl 4|5 engaging a notch in the element 4|3.For convenience in illustration, a separate friction drive is-sho'wn forthe manifesting means in each denominational order, but it is obviousthat a cornmon driving means which is capable of frictionally drivingthe manifesting means in the various denominational orders -could alsobe used.

Pawl 4| 5 is urged counter-clockwise (Fig. 2) about its pivot 4|6 byspring 4|1 into engaging relation with the notches in element 4|3 toarrest the scanning switch and the manifesting wheel 4|| in any one ofthe positions l to 9" and "0 as required by the digit value representedby tlie related denomination of the accumulator. A magnet 420 in theanode circuit of a control triode 42|, shown here as the lefthand triodeof a twin triode, tube 422, of the aforementioned 2G51 type, will beenergized to move the pawl 4|5 out of engagement with the element 4|3and free the manifesting wheel 4|| and the scanning switch 4 |2 formovement whenever the control triode 42|-oonducts.

Control triode A42|, which controls the position of the pawl 4|5, hasits anode `connected over thev winding of magnet 420 to the terminal423, to which +300 volts is applied, andv has its cathode connected toground over a vresistor 424 of 3,900 ohms.

Grid 425 of triode V42| is connected tothe read-out scanning switch 4|2and has potential applied thereto as follows. The scanning switch 4|2,as it rotates, engages successively oneafter another of a series ofcontacts connected to digit-representing lines which are 'connected overresistors, as 426, of 2.2 megohms, to various ones of the anodes of theright and left triodes of the cascaded trigger pairs. Depending uponwhether the trigger pairs are"on or of, the anode potentials of theirleft and right triodes will be either at +250 volts or at a lowerpotential resulting froml the drop across the anode resistors ofconducting triodes. The pattern of the resistance network connectionsvfor each denominational order is shown clearly in Fig. 2 and is soarranged that, for any digit represented by the combination of off andon" conditions of the cascaded trigger pairs, the line corresponding tothat digit will have a potential which is less positive than that of anyother line. By adjusting the cathode potential of the triode 42|, thisleast positive potential can be made to be the only one which will .beeffective to bias the triode 42| to cut-off, thereby deenergizing themagnet 42-0 and allowing the pawl 4|5 to engagevin the notch in element4|3. Ac'- cordingly, as the read-out scanning switch 4|2 is driven overits related contacts, itl will aping digit in reading. position, asindicated by the arrow 421, where they reman as long as cut- 2l ergizemagnet 420, which moves the pawl 4|5 from engagement with the element4|3 and frees the digit-'manifesting wheel 4|| and the scanning switch4|2 for further movement until the scanning switch engages anothercontact which is at cut-off potential.

The potential of the cathode of control triode 42| is adjusted by asecond triode 43B, which is the right triode of the twin triode, tube422, connected f to resistor 424. The anode of this second triode 430 isconnected directlyA to the '+300-voltterminal 423, and the cathode ofthe second triode 430 is connected to ground over the resistor 424.

Grid 43| of triode 430 derives its potential over an adjustable tap 432from resistor l433, which is connected between the anode potentialsupply conductor 225, for the cascaded trigger pairsfand ground. Byadjusting the tap 432. the potential on grid 43| can be made such thatconduction in triode 430 will raise the potential of the cathode oftriode 42| to a value which will be less positive than all but one ofthe potentials, the cut-oi potential, which are applied to' its grid 425from the read-out scanning switch 4|2.

The second triode 430 has another very important function; namely, thatof serving as a compensating means in the indicator control tube circuitto compensate for variations in potential applied to the anodes of thecascaded trigger pairs. Since the potentials sensed by the read-outscanning switch 4|2 and applied 'to the grid 425 are derived from theanode potential supply for the cascaded trigger pairs over conductor225, variations in this potential would cause variation in the gridpotential and possible misoperation of the digit-manifesting means.However, since the grid 43| of the second triode 430 is also supplied,through its tap 432 to resistor 433, with potential from the anodepotential supply conductor 225, variations in the anode potential supplywill cause a variation in the conductivity of the second triode 430,which will provide a compensating variation in the cathode potential oftriode 42| to maintain the relation between the cathode and gridpotentials of this triode substantially constant'despite variation inthe potential supplied to the anodes of the cascaded trigger pairs.

The digit-manifesting means for the tens denominational order, as shownin Fig. 3, 'and for any other orders which might be provided in theaccumulator, are controlled and operate in the same manner as describedabove.

The claims of the instant application are conned to the accumulator perse. Claims to the impulse generator are presented in a divisionalapplication, Serial Number 215,483, and claims to the data-indicatingmeans are presented in another divisional application, Serial Number215,484.

While the form of the invention shown andl described herein is admirablyadapted to fulfill the, objects primarily stated, it is to be understoodthat it is not intended to coniine the invention to the one form orembodiment disclosed herein, for it is susceptible of embodiment ofvarious other forms.

What is claimed is:

. 1. In combination, four electronic devices, each operable alternatelyto on and to oil condition in response to impulses impressed thereon,and including means to produce potential changes each .time the devicechanges from either condition to the other, said devices by their on andoff conditions, in combination, representing the digits l and 9 to ."0;circuits connecting the devices in series and enabling a potentialchange', produced by every operation of a device to said oi condition,to be transmitted as an impulse to the next device-of the series tocause an operation thereof; means to impress input impulses on the rstdevice of the series; a unidirectional circuit connecting the fourthelectronic device in the series to the third electronic device in theseries for transmitting a potential change, produced by the fourthelectronic device as it is operated to on condition, as an impulse tothe third electronic device to cause it to operate; and a secondunidirectional circuit connecting the fourth electronic device of theseries to the second electronic device of the series for transmitting'apotential change, produced by the fourth electronic device Aas it isoperated to oi condition, as an impulse to the second electronic deviceto cause it to operate; said series connections and two unidirectionalconnections cooperating to enable the four electronic devices to operateto accumulate amounts in the decimalnotation by causing the electronicdevices, in combinations, to progres# sively represent the digits l to"9 and 0 and to return to any particular digit-representing combinationafter ten impulses have been applied to the input means.

2. In combination, four pairs of electron discharge devices; circuitscross-connecting each pair of devices to form a trigger pair operablea1- ternately to on and to 01T condition in response to impulses andincluding means to produce potential changes each time the pair changesfrom either condition to the other, said trigger pairs, by combinationsof on and off conditions, representing the digits l vto 9 and 0;circuits connecting said trigger pairs in cascade to transmit thepotential change, produced by a trigger pair assuming its off condition,as an impulse to the next trigger pair of the cascade to cause it tooperate and change its condition; means to preset the trigger pairsvwith the rst, third, and fourth trigger pairs in said oil condition andsaid second trigger pair in said on condition; an input circuit uponwhich input impulses are applied to the iirstv trigger pair; aunidirectional feed-back circuit connecting" one of the devices of thefourth trigger pair to the third trigger pair to enable an impulse to besent to the third trigger pair from the fourth trigger pair each timethe fourth trigger pair operates to said on condition; and a furtherunidirec# tional feed-back circuit connecting the other of the devicesof the fourth trigger pair to the second trigger pair to enable animpulse to be sent to the second trigger pair each time the fourthtrigger pair operates to said off'condition.

3. In combination, four pairs of electron discharge devices, each ofsaid devices containing at least an anode, a cathode, and means to con-ltrol conduction therebetween; circuits for applying operating potentialsto the devices and including an impedance in the circuit to each anode;trigger connections cross-connecting the anodes and the conductioncontrol means of the devices of each pair to form them into a. triggerpair which will operate in on condition when current is conducted in oneof the devices and in off condition when current is conducted in theother of the devices; circuits connecting the trigger pairs in cascade,the cascade circuits between .trigger pairs extending' from the anode ofateneo? said other device of a .pair to the conduction control means ofboth devices vof the next pair of the cascade, for transmitting theanode potential drop, as `the trigger pair turns to its off condition,to the next trigger pair to cause an operation thereof, the cascadecircuits between'the first and-second trigger pairsand the second andthird trigger pairs including an isolation impedance. in series witheach of the conduction control means of the devices in the second .andthird trigger pairs; means to apply input impulses to the conductioncontrol means of the first trigger pair; alrst feed-back circuitvcontaining a unidirectional device and extending from a mid-point ofthe anode impedance of the other device of the fourth trigger pairdirectly toA the conduction control means of the other device of thesecond trigger pair of the cascade whereby to enable a portion of theimpulse which is generated across the impedance to be applied directlyto the conduction `control means of the other device of Y,the secondpair to turn the second trigger pair to on condition each time thefourth pair goes from on" Yto off condition; a second feed-,back circuitcontaining a unidirectional device and extending from a mid-point of theanode impedance of the one device of the fourth trigger pair directly tothe conduction control means of the other device of the -third triggerpair of the cascade whereby to enable a portion of the impulse which isvgenerated across that impedance to be applied directly to the.conduction control means of the other device of the third trigger pairto turn the third trigger pair to on condition each time the fourthtrigger pair goes from off to on condition; said trigger connections,cascade connections, and feed-back .connections enabling the triggerpairs to count in the decimal notation and represent digits l to 9 and 0by combinations of their on and o conditions.

4. In a device for counting in the decimal notation, the combination offour pairs of electron discharge devices, each of said devicescontaining at least an anode, a cathode, and means to control conductiontherebetween; circuits for applying operating potentials to the devicesand including an impedance element in the circuit to each anode;.trigger connections cross-connecting the anode-s and 4conductioncontrol means of the devices of each pair -to form them into a triggerpair which will operate in on condition when current is conducted in oneof the devices and in off condition when current is conducted in theother of the devices, the trigger pairs by combinations of on and offconditions representing the Vdigits and l to 9; circuits `connecting thetrigger pairs in cascade, the cascade circuits between trigger pairsextending from the anode of said other device of a pair to theconduction control means of both devices of the next pair of vrthecascade, for transmitting the full vanode potential drop, as the triggerpair -turns to its "ofP condition, to the next trigger pair to cause anoperation thereof, the cascade circuits between the first and secondtrigger pairs and `second and third Vtrigger pairs including anisolation impedance element in series with each of the conductioncontrol means of the devices in the second and `third trigger pairs:means to preset the first, third, and fourth pairs to on condition andthe second pair to off condition; means to apply input impulses; totheconduction control means of the first trigger pair; a first feed-backcircuit extending from the mid-point of the anode 'impedance element ofthe other device of the fourth trigger pair directly to the conductioncontrol means of the other device of the second trigger pair whereby toenable half of the impulse-.Which is generated across the anodeimpedance element of the other device of the fourth pair each time thefourth pair goes from on to:off condition to be applied directly to theconduction control meansof the other device ofthe second pair to turnthe second pair to on condition, said feed-back circuit including abarrier-layer rectifier which is oriented to have a low impedance tonegative feed-back impulses from the fourth trigger pair but a highimpedance to negative impulses from the second pair; a second feedbackcircuit extending from the mid-point of the anode impedance element ofthe one device of the fourth trigger pair directly to the conductioncontrol means of the other device of the third trigger pair, whereby toenable half of the impulse which is generated across the anode`impedance element of said one device of the vfourth trigger pair, eachtime the fourth pair goes from off to on condition, to be applied to theconduction control means of the other device ofthe third pair to turnthe third pair to on c ondition, said second feed-back circuit includinga lbarrier-layer rectifier which is oriented to have a low impedance tonegative feed-back impulses from the fourth trigger pair but a highimpedance to negative impulses from the third pair; the isolationimpedance elements in the circuits to the conduction control means ofthe ,second and third pairs attenuating the effect of the feed-backimpulses on the .conduction control means of said one tubes of thesepairs and enabling half of the amount of ,impulses at the anodes of thefourth pair to .operate the second and third pairs, and the isolationimpedance elements for the conduction control means Yof the other tubesof the second and third pairs and the portion of the anode impedanceelements of the fourth ,pair Vbetween the anodes and the points to whichthe feed-back circuits are connected, cooperating with the rectiers toprevent impulses applied to the second and third pairs over .the cascadecircuits from causing unwanted trigger operations in the fourth pair,thereby enabling small, compact barrier-layer rectiers having lower backimpedance to be used in the feed-back circuits.

`5. In a device for counting in the decimal notation, the combination offour pairs of electron discharge tubes, each of said .tubes containingat least an anode, a cathode,.and means to control conductiontherebetween; circuits for applying operating potentials to the tubesand including a resistor in the circuit to each anode; triggerconnections cross-connecting the yanodes and control grids of the tubesof each pair to form them into a trigger pair which will operate in oncondition when current is conducted -in one of the tubes and in 01Tcondition when current is conducted in the other of the tubes; circuitsconnecting the trigger pairs in cascade, the cascade circuits betweentrigger pairs extending fromthe anode of said other tube of a pair tothe conduction control means of both tubes of the next pair of thecascade, for ltransmitting the full anode potential dropfas the triggerpair turns to its off condition, to the next trigger pair to cause anoperation thereof, the cascade circuits between the viirs't and secondtrigger 4pairs and second and third trigger pairs including Janisolation resistor lin series with each of the conduction control meansof the tubes in the second and third trigger pairs; means to preset thefirst, third, and fourth pairs to on condition and the second pair tooff condition; means to apply input impulses to the conduction controlmeans of the first trigger pair; a first feed-back circuit extendingfrom the mid-point of the anode resistor of the other tube of the fourthtrigger pair directly to the conduction control means of the other tubeof the second trigger pair whereby to enable half of the impulse whichis generated across the anode resistor of the other tube of the fourthpair each time the fourth pair goes from on to oli condition to beapplied directly to the conduction control means of the other tube ofthe second pair to turn the second pair to "on condition, said feed-backcircuit including a crystal rectier which is oriented to have a lowimpedance to negative feed-back impulses from the fourth trigger pairbut a high impedance to negative impulses from the second pair; a secondfeed-back circuit extending from the midpoint of the anode resistor ofthe one device of the fourth trigger pair directly to the conductioncontrol means of the other device of the third trigger pair, whereby toenable half of the impulse which is generated across the anode resistorof said one device of the fourth trigger pair, each time the fourth pairgoes from off to on condition, to be applied to the conduction A controlmeans of the other device of the third pair to turn the third pair to oncondition, said second feed-back circuit including a crystal rectifierwhich is oriented to have a low impedance to negative feed-back impulsesfrom the fourth trigger pair but a high impedance to negative impulsesfrom the third pair; the isolation resistors in the circuits to theconduction control means of the second and third pairs attenuating theeiect of the feed-back impulses on the conduction control means of saidone tubes of these pairs and enabling half of the impulses at the anodesof the fourth pair to operate the second and third pairs, and theisolation resistor for the conduction control means of the other tubesof the second and third pairs and the portion of the anode resistor ofthe fourth pair between the anodes and the points to which the feedbackcircuits are connected being in series with the rectiiiers between thesource of impulses applied over the trigger and cascade circuits to theconduction control means of the second and third pairs and the triggercircuits of the fourth pair and cooperating with the rectiers to preventthese impulses from causing unwanted 'trigger operations in the fourthpair, whereby small compact crystal rectiers having lower back impedancecan be used in the feed-back circuits; and said trigger connections,cascade connections, and feed-back connections enabling the triggerpairs to count in the decimal notation and represent the digit notation1 to 9 and 0 by combinations of their on and off conditions.

CARL F. RENCH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Potter, pages 110-113, 358 and 360 of Electronicsfor June 1944.

